a. Field of the Invention
The present invention relates generally to frames and similar structures that support growing plants, and, more particularly, to a coiled frame that trains the plant in a manner that allows control of apical dominance to be achieved in an efficient, cost-effective and low stress manner.
b. Related Art
Farmers and gardeners look for ways of increasing conditions and improving quality in their plants. Providing a plant with optimum environmental (e.g., water, light, soil/medium, CO2) and nutritional support can go a long way towards achieving these goals. Beyond meeting a plant's environmental and nutritional needs, gardeners also often explore and employ methods of training to take a plant's yield and quality to a higher level.
Certain fast growing plants, such as tomatoes for example, can benefit from increased branching. Also it can be advantageous to have evenly proportioned branches, as compared to apical dominance. Apical dominance refers to the process wherein the axillary buds (side or lateral shoots) remain dormant and are reserved by the auxin (plant hormone) that is produced by the apical shoot. When a plant's apical shoot is left intact and unbent the plant tends to take on a conical shape much like a Christmas tree, which is unsatisfactory for production of many vegetables and other crops.
Removing apical dominance is achieved by either cutting (also referred to as pinching, pruning, topping and heading off) or bending of the plant's apical shoot. Cutting or bending the apical shoot removes the auxin's inhibitory effect on the axillary shoots so that growth of the latter is enhanced. Depending on the desired size of plant, and in order to distribute hormones and resources as evenly as possible among the branches/shoots, further pinching or bending may be necessary. This results in an increased number of equally proportioned branches and aids in training the plant for improved quality and increased yield. The shape of a plant trained in this manner is often that of an inverted cone.
Removing growing shoots by cutting and pinching is perhaps the least time consuming method of training plants commonly employed by growers. Gardeners often use a form of shears to remove a growing tip (some may use only their hands and/or finger nails for smaller shoots). However, there are significant drawbacks to cutting a stem or stalk of a plant. First, an open wound left behind where cutting took place, leaving a plant exposed to infection or disease until the wound is healed. Second, growth vigor is lost while the plant repairs the injury and redirects growth hormone to other shoots/branches. In combination this results in lost time and growth opportunity during healing and redistribution of growth/hormone, which in turn may reduce yield and quality (if dealing with natural growing seasons), or may increase the time to harvest (if climate and environmental controls are in effect). As an additional drawback, auxins are transported down the stem to the roots; loss of auxin, due to removing an apical shoot, may result in less stimulated root growth and root branching.
An alternative to pinching/cutting is bending. This can take various forms, from simply folding a growth shoot over, to attaching it to stakes trellis, netting or wires (e.g., an espalier), wrapping and bending with wire (e.g. bonsai), pulling it down and applying hanging weights, tying it down with cordage and stakes, and so on. After a growth shoot is bent it will immediately begin turning itself vertical again due to the effect of gravitropism (plant shoots display negative gravitropism; when placed on its side, a plant shoot will grow up against gravity) and will soon require further bending. Bending is advantageous relative to cutting in that it does not create an open wound and no auxin is lost. The main drawback of bending is that when using conventional techniques it is often much more time-consuming than cutting. This is a particular problem in commercial operations dealing with large numbers of relatively fast-growing plants, where the labor intensive aspects of conventional bending approaches become greatly compounded.
Commercial growers also often use artificial lighting, in whole or in part, to expedite growth as compared with the natural growing season, and the cost of electricity creates the need to use the artificial light efficiently. Reducing the amount of time and electricity to produce crops requires that plants not be subjected to cutting for controlling apical dominance, in order to retain auxin and shorten the time from seed to harvest. Being able to adjust the orientation/angle of the plants may also help maximize utilization of light sources. Furthermore, for a variety of reasons pots or other containers are conventionally used to grow plants in commercial environments, and in order for a training technique/device to be most useful it is desirable that the containers remain individually mobile, rather being attached to trellises or other structures that interconnect plants such that they and their containers are not easily moved about.
Thus, while prior methods of pruning and training are effective in increasing the number of evenly proportioned branches and therefore productivity, the drawbacks/limitations that are inherent to such methods leave a significant void when it comes to overcoming apical dominance in a rapid and efficient manner.
Therefore, a need exists for a method and apparatus that overcomes apical dominance while reducing the amount of stress placed on the plant from training. Furthermore, there exists a need for such a method and apparatus that is easy to learn and that can be implemented in a rapid and efficient manner, especially when working with multiple plants. Still further, there exists a need for such a method and apparatus that facilitates efficient and economical use of lighting and other growing resources. Still further, there exists a need for such a method and apparatus that may be implemented using structural components that are economical to manufacture and transport, and that are adequately durable and long-lasting to permit reuse if desired.